Jack



Filed Feb. 3, 1959 2 shets-sheet 1 I ATroRNEY,s.

Jan. 2, 1940. c. M. ELLENBx-:RGER

4JACK Filed Feb. s, .1959

III/I1 Ilm In Patented Jan. 2, 1940"A UNIT-izo g s'rli'rflas` lwrisiir` oren-CE f non l clarence M. Euenberger, Pendleton, ma. application February s, 1939, serial No. 254,366 15 c"1inn 1.-1. (c1. Ygt4- 106) l man operating lever. One of the dogs, which may forconvenience be called the retaining dog, is directly associated with the body and is arranged to' cant `on the rod and grip it frictionally when the body and rod tend to move relatively under 15 the load which the jack sustains. 'rhe'operanng lever acts between the body andthe other dog, which may be called the fulcrum dog and which is arranged to canton and grip the rod .when the llever'is operated to cause the body and rod to y move relatively against the load. Upon movement of the lever in the opposite direction, the

p -Iulcrum dog moves4 along the rod to a new position thereon, the retaining dog meanwhile preventing relative movement of the rod and body -u .under the influence of the load. To release such a jack while under load the only method heretofore zavailable has involved forcibly moving one or both dogs to uncanted position to release their Y grip on the rod .and permit uncontrolled relative .30.. movement o! the head and rod under the inuence of the' load.

It is the primary object of my. invention to produce a jack of this kind in which it is possible to control relativ'movement Aoi! the body .and rod 35. under the influence ofthe load. Anotherobject ofv my invention is to produce a jack of this type which will be simple in construction and positive in operation, and which can be economically manufactured. e ,4 In embodying my invention in a friction jack,

I provide releasablev means capable oi overcoming the normal tendency of the dogs to-assume a canted position and operative only through a limited range o'f movement of each dog relative to 4l' the rod. Conveniently this means takes the form of leal-springs'mounted in' the body ffand acting respectively upon the two dogs. The spring associated with the retaining dog acts,: when thatv dog is relieved of the load, to move it for a limited 50 distance away from engagement with theA body and into anew position on the rod. The spring associated with the fulcrum dogmay merely act to overcome the normal tendency oi that dog to assume a canted position, so that such dog can 5g be moved along the by the lever in the direction inwhich its movement is normally prevent. ed. When the, fulcrum dog has been i moved through the range over which its associated. spring is effective it cants and grips the rod, and a slight continued movement of the lever relieves the re- 5 taining dog of its load so that its spring can move it to a new position on the rod.4 The lever is then swung in the opposite direction to permit relative.. movement of the body and rod under the influence of ,the load until the'body again en- 10 1 gages the retaining dog in tliellatters'v new position.

, For purposes of explanation I have chosen to illustrate my invention as embodied in an .automobile jack of the bumper'type, but itis to be l5 understood that my invention is not'limited to such a device. In a bumper-'type automobile jack the rod is usually the stationary element oi the jack andis supported in vertical positiony from the ground.' The body is in the form of 2b a head adapted to engage a n automobile bumperand to travel upwardly on the rod to'raise the downwardly applied load.

The accompanying drawings illustrate a bumper jack embodying my invention: Fig. 1 is a long5 gitudinal section through the jack on the line I-i of Fig. 2, showing the parts in the positions they` occupy just prior to a head-lifting movement of the operating lever; Fig. 2 is a front elevation of theheadof the jack; Fig. 3 is a fragmental 30A view generally similar to Fig. 1 showing the coridition existing at the conclusion of a head-lifting movement of the operating lever; Fig. 4 `is a view similar to Fig. 1 but showing the jack arranged to lower' the load under control; Fig. 5 35 vis a view similar to Figs. 3 and 4, showing, in full lines, the condition existing as the operating lever v:lust reaches its limit of upward movement in a head-lowering operation and, in dotted lines, thel condition existing immediately thereafter; Fig. o 6 is a view similar to Fig. 5, showing the-condition existing at the end-of a downward movement of the operating lever in a head-lowering operation;

Figs. 7 and 8 are horizontal sections on the lines l-'I and 8-8 of Fig. l; and Fig. 9 is a.vertical section on the line 9-'4 of Fig. '1.

vThe jack illustrated in thedrawings comprises a base plate III having at its center a hemispherical depression for the reception of the rounded lower e'nd of the circular rod I I. the jack, which is slidable relatively vtov the rod I I, is in the form of 'a head I2, conveniently made as a hollow casting the bottom and top walls of which have aligned openings ,slidably receiving g the `rod II. all as is clear from Fig. 1'. The head 65 'me body of so I is provided with an upward extension I3 formed at its top with one or more lateral projections Il shaped to engage the bumper of an automobile.

Mounted within the head I2 and upon the rod f II are the retaining dog I5 and the Iulcrum dog I6, the former being above the latter in this particular construction. The retaining dog I5 is provided with a lateral extension I1 disposed beneath a downwardly extending abutment I8 provided interiorlyv of the head I2 and so arranged as to engage the extension I1 at a point spaced f from the axis ofthe rod II. As a result of this. arrangement, 'any load applied to the-dog I5 through the abutment I8 will tend to cant the dog upon the rod Il and to cause it to I'grip the 'rod with a rm frictional engagement.

The fulcrum dog I6 is provided with a lateral extension 2n disposed beneath the extension n of the upper dog and adapted to co-operate with the inner end of a swinging lever 2l pivoted in the housing I2 as by means of a pivot pin 22. Desirably, the lever 2| is relativelyshort and'is provided at its. outer end with a socket adapted to receive a removable operating handle 23. The extension and lever 2| are so formed that the lever may exert either an upwardly directed force or a downwardly directed force upon the dog I6. To this end, the lever 2| is hown as provided with an inwardly extending ange 2l overlying the dog-extension '20 and with two laterally Aspaced ears disposed beneath the dog-extension 20. A lug 26 on the extension 28 is received between two ears 25 and both strengthens the extension and prevents rotation of the dog I6 relative to the head I2 about the axis of the 'rod II. l

Whenever a load is transmitted through e or the 'other oi the dogs I5 and I6 from the head to the rod II such load, being eccentrically applied to the dog, will tend tocause the dog to cant and grip the rod frictionally. The downwardly directed force applied eccentrically to the retaining dog I5 through; theabutment I8 and the upwardly directed force applied concentrically to the dog and representing friction between it and the rod I I form a force couple tending to rotate the dog 'in a clockwise direction (Fig. 1). This vertical-force couple is opposed by a horizontal-force couple consisting of the oppositely directed reactions of the rod IIl upon the dog at the ends ofthe rod-bearing therein.-

Obviously, the magnitude of the latter reactions, and consequently the-magnitude of the frictional force opposing movement of the dog on the rod,'can be increased by decreasingthe arm of the horizontal-force couple-i. e., by decreasing the eiective' length ofthe rod-bearing in the dog. Again obviously, the dogs must be strong enough to sustain the .forces which will be imposed upon them imuse.

With these obvious considerations in mind, the

`do'gs are designedy as indicated in the drawings.

They. are conveniently formed asv steel ,castings proportioned to sustain the stresses which theyA will have to bear in use.' At its lower end on-the side adjacent the .extension` (111 or 2l) and at its upper end on the opposite Side, the bore of.

, each 'dog is`relieved as indicated at`23 to shorten lthe effective length or the rod-bearing inthe dog ,when the dog is canted under the downward load imposed upon itsl extension. The axial depths of these reliefs will depend upon the dis-A tance between the axis of thefrod Il and the point at which load is applied to the dogi Specincally,` as will be apparent upon drawing a .theheadf simple force diagram, the ratio'of the eiective length yoi the rod-bearing with the dog under -load vto the distance between the rod-axis and the point at which the load is applied to the dog should beless than twice the coefficient 'of friction between the rod and the dog at the points of interengagement thereof. V A

Pivotally mounted within the head I2 'above the lever 2| is a spring-carrier 30 to which arey secured a pair of leaf springs 3| and 32 that extend inwardly between the two dogs |5 andY I6. The upper spring 3| completely embraces the rod II, and on the remote side of such rod is provided with a slot receiving a lug 33 projecting downwardly from the dog I5. Beneath the spring 3|, the lug 33 is provided with lateral projections 34 (see Fig. 9) which prevent the spring 3| from moving downwardly relatively to the dog I5. Engagement 'of the spring 3| with the lug 33 holds the dog I5 in ilxed position about the axis of the rod |I. The lower spring 32 has its 'free end bifurcated, the bifurcations extending inwardly on opposite sides of the rod suiciently far to bear upon the lower dog |6 at diametrically opposite points. The lower surface of the dog I5 isformed, as indicated at I5 so that an upward force exerted upon it by the spring 3| will be. applied substantially in alignment with the axis of thefrod II and therefore will not tend to cause the dog to cant on the rod. For the same reason, the lower dog is formed to provide a y raised spring-engaging portion I6'. g

The spring carrier is oscillatable so that the free ends of the springs 3| and 32 may exert either upward ordownward forces on the dogs I5 and I6. To this end, the spring carrier 33 is pivoted in the head |2, as by.means of a piviot pin 35 and its upperfsurface is provided with a groove 36 which receives a finger 31 on a control ymember 38. The control member 38 is pivotally mounted in the head I2 on an axisy above the spring carrier 30 and, on hopposite sides of the iinger 31, is provided with ears 39 and 38.

Associated with the ,lower dog I6 is so'me means, here shown as a spring 4|, tending normallyto cant the dog I6 into locking position on the rod II. As is clear from Fig. 1, .the spring 4| is formed f a bent strip of steelxattached to the dog I5 and bearing against the side of. the rod II at a point below the dog and opposite the dogextension 20. g f

In Figs. 1, 2, and 3, the control lever 38 is in the position itY occupies when the head I2 is being raised. In this position, Athe spring-carrier 33 is rocked about its axis of pivotal .mounting to the limit of `lits movement in a clockwise direction, and the spring 3| bears'upwardly-on the dog I5 with anaxially applied force. The reaction oi the spring 3| upon the carrier 3 0 tends to rotate leld in position and the spring 3|, supported from below by the spring '32, exerts an upward force on the dog- I5 and'maintains the extension I1 thereof in engagement In Fig. i, the operating'llever 2| and the dogs' I5 and I 6 are illustratedl in' the respective posiwith the abutment I3 on l tions theyvoccupy at the limit of a downward movement ofthe handle 23. When the handle 23 is swung upwardly, the iiange 24 on the operating lever 2| engages the projection 20 on the -dog Il and applies to the dog an eccentrically disposed downward force which co-operates with that exerted by the spring 4| tending to cant Y the dog I6 upon the rod Il. Because this canting tendency causes the dog I6 to grip the rod II frictionally, the `dog can not move downwardly Aon the rod. Instead, the lever 2| fulcrums at the point of engagement between the flange 24 ,and the dog-extension20 and, operating asa lever of the second class, moves the head I2 upwardly. During this upward movement, the

spring 3| acting' on the dog I5 causes the projection I1 to remain in contact with the abutment I3 on the head, and the dog I5 therefore moves upwardly with the head as the handle 23 is raised. At the limit of upwardmovement of the handle 23, the parts occupy the respective 'positions illustrated in Fig. 3.

move upwardly also until the dog I6 'engages the lower leaf spring 32. When the operating handle 23 is again moved upwardly, the cycle of op Arations is repeated, upward movement of the ating handle irst canting the dog I6 into gripping engagement witli the rod II and subsequently raising the head.

When it is desired to lower the head, the control member 33` is swung in a. c1ockwise direction to the position illustrated in Figs. 4 and 5, thus forcing the free ends of the springs 3| and 32 downwardly. As in the case when the vcontrol lever 38 is in its up position, the reaction of the inner side wall ofthe groove 36 upon the end of the :dnger 31 tends to rotate the control member 33, this timei in a clcokwise' direction, such rotation being limited by engagement of the ear 33' with the outer side of the spring carrier 30.

With the'control lever 38 moved from its up to its down position, the parts will normally EISy occupy the positions illustrated in Fig. 4. The upper leaf spring 3| acting on the head 340i the lug 33, will exert a downwardly directed forcei on the upper dog I5 tending to release that dog and move it'downwardly on the rod `I I. This tendency is more than` overcome, however, by the' load on the abutment l1 which maintains the/dog I5 in canted position. AThe lower leaf springi32I acts on' the raisedportion I6 of the dog I5 with a \forcegreat eno'ugh'to overcome the canting-eirect of thespring 4|, and tends to move the dog |81d downwardly on the shaft, its

eiect being opposedby the weight of the handle If the handle 23 is now raised, the spring 32 forces thefdog I6 downwardly on the rod until' 1 such spring engages the abutments 50 (s'ee fulle line' position in Fig. 5)-, and the dog I6 is thereafter free to cant and grip the/rod upon a continued `upward movement of the` operating handiei 'A '3 When' upward movement of the handlef23 is continued, as from vthe full-line position to the dotted-line position in Fig. 5, the dog I6, being prevented in its canted position from moving downwardly on the rod, acts as a fulcrum 'for the lever 22 and the head I2 is raised. This raising of the head frees the extension I1 of the dog I5 from the load previously applied through the abutment I8 and consequently relieves the dog I5 of 'the force which was maintaining it in ,canted position against the releasing effort exerted upon it by the spring' 3|. Upon being relieved of force applied to its extension I1, vthe dog I5 is moved downwardly `on the rod I I Auntil the spring 3| engages the spring 32, or. into the dotted-line position indicated in Fig. 5.

` The load is now beinglsupponted through the lever 2|, which can be 'swung' under control of the handle 23.to permit downward movement of the head I2 on the rod II under the influence of the load and at the rate desired'.- As the.

head moves downwardly on the?rod the abutment |8'eventual1y'engages the projection l10n' the upper dog I5 and cants such dog into its locking position; whereupon the parts will occupy the positions illustrated in Fig. 6. During descent of the head I2, the abutments move downwardly with it and permit the spring 32 to exert itsreleasing effort ion the lower dog I3. Since, during lowering movement of the head, the dog I6 is sustaining the load and'is canted into locked position by the downwardly directed force applied to its extension 2|! by the innerend of the lever 2| the downward pressure exerted upon it by the spring 32 can not release the dog. However, when the abutment I8 again engags the projection I1 (s'ee Fig. 6) and transfers the load to the. upper dog I5, the lower vdog f|6 is relieved of the load; and upon the ensuing upwardsmovement of the handle 33 that dog moves downwardly under the inuence of thespring 32 until the latter engages the abutments 50, whereupon the parts carried by. the

head are restored to theI positions shown in f ull lines in Fig. 5 ready for another controlled downlward movement of the head.

Foxjpurposes ofl assembly, the head I2 is shown ias providedin `its rear wall with-an opening l large enough for the insertion of the dogs I5 and, I6 and of other parts. In the completed jack, this opening is closed, as by a'cover plate 56 conveniently formed of elastic sheet-metal and heldin place byshoulders 51 on the head I2,

the cover plate bei'ng provided at its edges. with off-set portions 58 eng-aging behind said shoulders. (See Fig. `'1.)

Since the dogs are heldin` placel in the head only as the result of their bearing on the, rod II,

it is' advisable to Sprovide means preventing the rod from being withdrawn from the dogs. this purpose, Vthe metal of the rod, at each end thereof, may be displaced to form an outward projection suchas the flange 50 shown at the upper end of the rod or the boss BI at the lower end, of the rod. To increase the range 'of ad justment of the jack, theinternal diameter'of the head-extension l claim as my invention; l i f l. A jack, comprising a rod, a head slidablesdn said rod`. an 4upper dog also slidable onsaid rod,4

an abutment carried by said head, said abutment I3 may be made larger enough td clear the` ange 63.

being ,positioned to engagesaid upper d og at an f eccentric point and cant -itfint gripping engagement with said rod when said head tends to move dog and being adapted to fulcrum thereon at an to saiduppervdog at a point on the opposite side eccentric point vto cant the lower dog tol gripping engagement with said rod, the outer end.

ofsaid lever being-provided with a handle portion extending laterally from the head, spring means carried by said lowerrdog and engaging said rod to bias such dogv toward canted position, two superposed leaf springs carried .by said head and having their free ends disposed between said dogs, means associated with said leaf springs and selectively operable to cause their free ends to exert either upward or downward forces, the upper one of said leaf springs being connected of said rod from the abutment on said head, and a second abutment on said head positioned to limitdownward movement of the' free end of the lower one of said leaf springs.

2. A jack comprising a rod, a-head slidable on said rod,- an upper dog also slidable on said rti, an abutment carried by said head, said abutment being positioned to engage said upper dog at an eccentric point and cant it into gripping engagement with said rod when said head tends to move downwardly, a lower dog slidable on said ro'd, an operating lever pivoted in said head', theinner end o f said 'operating lever engaging said lower dog and being adapted to fulcrm thereon at an eccentric point to cant the lower dog into gripping engagement ywith said rod, the outer end of said lever being provided with a handle portion extending laterally from the head, two superposed leaf springs carried by said head. and having their free ends disposed between said dogs, means associated with said leaf springs and selectively operable to cause their free ends to exert either upward or downward forces, the upper one of said leaf springs being connected to said upper dog at a point on the opposite side of said rod from the abutment on said head, and a second abutment on said head positioned to limit downward movement of the free end of the lower one of said leaf springs.

3. A jack, comprising a rod, a head slidable on said rod, an upper dog also slidable on said rod,

an abutment carried by said head, said abutment being positioned to engage said upper 'dog at an eccentric point and cant it into gripping engagement with said rod when said head tends to move downwardly, a lower dog slidable on said rod, an

operating lever pivoted in said head, the inner end of said operating lever engaging rsaid lower dog and being adapted to fulcrum thereonv at an eccentric point to cant the lower dog into gripping engagement with said rod, the outer end of ysaid lever being provided with` a handle portion extending laterally from the head, relea'sable means acting on said upper dog and tending to release it from canted position and to move it toward said lowerdog, a second releasable -means -acting on said lower dog/and tending to move it downwardly on said rod,- an operating lever pivoted in said head, a second dog on said rod, said lever being operatively connected 4to said dog at an eccentric point thereon'whereby` said -second dog will cant and grip said rod frictionally when subjected to a downward load applied by said lever, and means operable to move eachl 'of said dogs a predetermined distance down- `wardiy on said rod when the dog is relieved of load. P

6. In a friction jack having a body and a rod movable relatively to eachother longitudinally of the rod, la. pair of dogs on said rod, and means associated ,with one of said dogs and selectively controllable to bias such dog for movement .in either direction longitudinally of said rod.

'7. In a friction jack having a body and a rod movable relatively to each other longitudinally movable relativelyto each other longitudinally of the rod, a dog on -said rod, 'a d,a leaf spring -carried byV said body and enga 'saiddog to bias it for movement on said rod, said spring-and dog being provided with interngaging provisions preventing the` dog from rotating relatively to the head about the axis of the rod.

9. In a friction jack havinga body and a rod movable relatively to each` other longitudinally of the rod, an operating lever pivoted in said body, a Vdog slidable on said rod and having an ececntric portion engaging said body, a second dog operatively associated with said lever and slidable on said rod, and spring means 4carried by said second dog and bearing yieldingly on said rod to bias said second dog toward .canted 'position on the rod.

10. The invention set forth in claim 9 with th addition of releasable means carried by said body and acting on said second dog to overcome the dog-canting eil'ort of vsaid spring means.

11. In a friction jack having a body and a rod movable relatively to each other longitudinally of the rod, an operating lever pivoted in said body. a dog slidable on said rod and having an 'eccentric portion engaging said' body, a second dog operatively associated with said lever and slidable onA said rod, spring means carried by said body and exerting on said second dog a 'force directed longitudinally of said rod, an abutment on said body limiting the action of said spring means, and fmechanism associated with said spring means for moving it out of engagement with said second dog.

12. In a friction jack having a body and a rod movable relatively to each other longitudinally of the rod, an operating lever' pivoted in said body, a dog slidable on said rod and having an ,eccentric portion engaging said body, a second f dog operatively associated with said lever and slidableion said rod, and means associated with said first dog for moving it towardsaid second dog.

13. In emotion 'jack havinga body and a rod movable relatively to each other longitudinally of the rod, an operating lever pivoted in said body, a dog slidable on said rod and having an eccentric portion engaging said body, a second dog operatively associated with said leverA and slidable on l gleam said rod, andmeans carried by said body and sedos lectively operable-to bias said nrst dog for movement either toward or away from said second 14. In a friction jack having a body and a rod movable relatively to leach other longitudinally of the rod, an operating lever pivoted in said body, a deg slidabie on said rod and having an eccentric portion engaging said body, a second dog operatively) associated with said lever and direction away from said second dog. C V

15. In a friction Jack having a body and a r movable relatively to each other longitudinally of the rod, a pair ot dogs on said rod, a springcarrier pivotaliy mounted in said body on an axis 5 displaced from said rod. a leaf-springl carried by said carrier and acting on one of said dogs, said carrier being provided with a- V-groove, and a control mbmber having a portion disposed in said groove and engageable -with' either of the vwalls m thereof to rock said carrier and control the action of said spring on the associated dos.

' vcrimnrrcis: vM. En.. 

